1. Field of the Invention
This invention relates to alkyltin thermal stabilizers for halogen-containing resin compositions. More particularly, the present invention relates to alkyltin sulfanyl mercaptocarboxylates having from one to three terminal thiol groups and which are suitable for thermal stabilization of polyvinyl compositions.
2. Description of the Prior Art
British Patent Specification No. 866,484 generically discloses alkyltin sulfanyl derivatives having terminal thiol groups, which are said to stabilize vinyl resins against the degradative effects of both heat and light. However, no experimental data is provided to quantify these claims for any of these compounds.
Non-thiol terminated alkyltin stabilizers are also known. For example, dimethyltin bis S,S(2-ethylhexanol thioglycolate) and di-n-butyl bis S,S(2-ethylhexanol thiolglycolate) are both commercially available. One of the most effective thermal stabilizers is a blend of dimethyltin bis S,S (2-ethylhexanol thioglycolate) and methyltin tris S,S,S(2-ethylhexanol thioglycolate). These compounds are also commercially available.